Thoroughly cleaned flame sensor and burner cabinet. Inspected igniter to make sure it was operational. Adjusted gas valve to 7 for use with propane. Eventually got package unit to ignite and tested unit operation. After a few minutes of operation Flue CO reading was about 2500 ppm and air flow inside the house was reading about 14 ppm and climbing indicating there was a leak in the heat exchanger. Removed blower motor and inspected heat exchanger. After several tests it was determined heat exchanger is leaking before going to he inducer motor in right burner tube. Would STRONGLY advise against system use.